Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In some systems, the network uses system information to broadcast important information to all UEs in a cell (e.g., information used in requesting network access in the cell), which is typically signaled in system information blocks (SIB) and/or master information blocks (MIB) defined by the access technology. Information that is broadcast in a SIB can change, and a value tag in a SIB is used to indicate change of the SIB to a UE. In particular, a range of values can be used to indicate change of a SIB such that when a broadcasted value tag matches the tag stored in a UE, the UE need not read the broadcasted SIB and instead can use a stored SIB (e.g., or stored information from a prior SIB), which can allow for saving UE power, conserving radio resources, avoiding unnecessary delay in accessing a network, etc. In one specific implementation, in UMTS, SIB5 value tag can have values 1 to 4, which cycle as the SIB5 is modified in the cell. Thus, if a UE returning to the cell encounters a value other than that previously stored by the UE, the UE can receive, process, and store SIB5 from the cell.
It is possible, however, that the network implements certain features, such as dynamic activation/deactivation of high speed random access channel (HS-RACH) and/or high speed forward access channel (HS-FACH), which uses SIB5 modification to indicate the activation/deactivation depending on whether common enhanced data channel (E-DCH)/high speed dedicated shared channel (HS-DSCH) information is included or not. Thus, the SIB5 content can be toggled and/or changed frequently, and 4 value tags may not be sufficient to reliably indicate a change in SIB5. In particular, a UE may leave a cell, and that cell may completely cycle through value tags before the UE returns, in which case the UE may read the same value tag, and thus does not read SIB5 though SIB5 may have changed. This can result in the UE not being able to communicate with the cell.